1. Technical Field
The present invention relates to an illuminating device provided with a light guide plate and a light source, a liquid crystal display device provided with the illuminating device, an electronic device provided with the liquid crystal display device, and a manufacturing method of the light guide plate.
2. Related Art
A liquid crystal display device provided with a transmissive liquid crystal panel includes an illuminating device with a light source whose light emitting surface faces a side end surface as a light incident portion of a light guide plate, wherein a liquid crystal panel is arranged in a superimposed manner on a light outgoing surface side of the light guide plate. In relation to such an illuminating device, a configuration has been proposed in which a groove is formed with a laser beam on a surface opposite to the light incident surface in the light guide plate for the purpose of enhancing illumination light emitting intensity (see JP-A-2008-20888).
When a groove is formed with a laser beam as in JP-A-2008-20888, the light guide plate is displaced while the light guide plate is irradiated with a laser beam in a state where the light guide plate is placed on a stage. On this occasion, if a focus position of the laser beam is not precisely set on the surface of the light guide plate, sizes such as a plane area, and a depth of the groove are changed, and a quality of the light guide plate is varied.
However, the light guide plate is a translucent resin plate formed by molding, and therefore, the thickness is varied for each light guide plate. For this reason, there are problems in that a relationship between the surface of the light guide plate on the stage and a focus position of the laser beam is varied for each light guide plate when the light guide plate is irradiated with the laser beam, and that the quality of the light guide plate is varied.